Light and strong aircraft structures

INNOVAIR is Sweden’s national strategic innovation programme for aeronautics. It coordinates and supports stakeholders from industry, universities, institutes, associations and government agencies active in the aeronautics sector.

The main objective is to promote favorable conditions for a strong aeronautics industry in Sweden and to strengthen this sector through increased collaboration, research and information dissemination.

GKN Aerospace Sweden belongs to the GKN Group, a global company with 56 000 employees in 33 countries. The group is divided in three divisions: Aerospace, Driveline and Powder Metallurgy.

GKN Aerospace Sweden (formerly Volvo Aero) has about 2 500 employees in Sweden, and belongs to Engine Systems. The company has production facilities in four countries: Sweden (Trollhättan and Linköping), Norway, Mexico and the USA. The headquarters is located in Trollhättan, Sweden.

Laser-welded lightweight structures can make aircraft engines much lighter without compromising strength. The technology saves fuel and reduces emissions, and the developer, GKN Aerospace, expects it to have a lot of traction.

For air transports, a good fuel economy and a small carbon footprint is all about weight. At the same time, an aircraft’s components have to be strong and able to withstand extreme strains.

”Making components stronger by adding material is not a feasible solution for the aerospace industry. We have been able to develop a unique laser welding technology for lightweight structures. It makes parts of the aircraft engine 10 to 15 percent lighter, and saves substantial amounts of fuel”, says Robert Lundberg, GKN Aerospace.

A Swedish innovation solves the dilemma

”Combining low weight and strength in the same technical solution is not trivial. The demands seemingly contradict each other, but we were able to challenge the boundaries of the materials and their performance by thinking outside the box. The fact that we are working on engines makes the task even more difficult, since the thermal and mechanical stress is so significant”, Robert Lundberg says.

”GKN Aerospace’s method for constructing laser-welded lightweight structures involves replacing heavy moulded components with components assembled from sheet metal, forgings and smaller moulds. We had to advance the laser welding technology, but also the welding simulations, which are crucial to predict deformations and residual stress in the component. This kind of extremely weight-optimized welded structures would not be possible to achieve without them”.

”In the end, we achieved a 10 to 15 percent weight reduction compared to conventional engine structures. Low fuel consumption is a powerful driving force in the aerospace industry, and there is a huge market for this kind of solutions. The structures have been included in the PW1000G engine family, which will be used in aircraft such as the Bombardier Cseries, Embraer E-Jet-E2, Mitsubishi MRJ and Airbus A320neo”, Robert Lundberg says.

”Welded lightweight constructions have many other applications as well: in space technology, energy production and the automotive industry, for example. As often is the case, an innovation from the aerospace industry can lead to important technology transfer”.

Strategic innovation programme for aeronautics

A technology in development passes through a number of stages over time (expressed as Technology Readiness Level, TRL). TRL 1 is basic research, while a technology at TRL 9 is fully commercialized. Illustration: INNOVAIR.

Air travel and transport have an important role to play in reducing greenhouse gas emissions. There has been steady progress, and the fuel consumption of an aeroplane has been cut in half in fifty years. Flights generate 2-3 percent of the global carbon dioxide emissions today, and in Sweden, 1 percent of the total is caused by domestic flights. The EU is paying a lot of attention to the development of fuel-efficient aircraft, and several member countries have EU-funded collaborative projects that bring academy, authorities and industry actors together.

INNOVAIR is Sweden’s national strategic innovation programme for aeronautics. The PW1000G engine programme is part of the structure for aerospace engineering innovation, and the PW1000G turbines will primarily contribute towards the ACARE (Advisory Council for Aviation Research and Innovation in Europe) environmental goals for the EU. At the same time, they meet INNOVAIR’s longterm goals to strengthen the aeronautics industry and its role as supplier to international projects.

”Innovation and technology development in military and civilian aeronautics follow a principle we refer to as ‘the oblique wave’; When a wave is set off, up to 15 years of development is required before it is ready for commercialization. It has to pass through every stage of technology readiness: idea, basic research, applied research, prototype, product development, field trials and so on. The lightweight structures of the PW1000G is a good example – but now, the product is ready. Since the environmental standards continue to develop, the demand for lighter and stronger components will only increase in the future. The lessons learned from PW1000G will be important in the next wave of technology development”, Robert Lundberg says.

The PW1000G turbine structure project has involved a number of actors beside GKN Aerospace, such as University West, Luleå University of Technology, PTC Innovatum, Swerea, Pratt & Whitney, Tooltec, Brogren Industries, Permanova Laserteknik and Midroc Automation.